title: Severe adult-onset asthma: A distinct phenotype.
abstract: BACKGROUND
  Some patients with adult-onset asthma have severe disease, whereas others have mild transient disease. It is currently unknown whether patients with severe adult-onset asthma represent a distinct clinical phenotype.
  
  
  OBJECTIVE
  We sought to investigate whether disease severity in patients with adult-onset asthma is associated with specific phenotypic characteristics.
  
  
  METHODS
  One hundred seventy-six patients with adult-onset asthma were recruited from 1 academic and 3 nonacademic outpatient clinics. Severe refractory asthma was defined according to international Innovative Medicines Initiative criteria, and mild-to-moderate persistent asthma was defined according to Global Initiative for Asthma criteria. Patients were characterized with respect to clinical, functional, and inflammatory parameters. Unpaired t tests and χ(2) tests were used for group comparisons; both univariate and multivariate logistic regression were used to determine factors associated with disease severity.
  
  
  RESULTS
  Apart from the expected high symptom scores, poor quality of life, need for high-intensity treatment, low lung function, and high exacerbation rate, patients with severe adult-onset asthma were more often nonatopic (52% vs 34%, P = .02) and had more nasal symptoms and nasal polyposis (54% vs 27%, P ≤ .001), higher exhaled nitric oxide levels (38 vs 27 ppb, P = .02) and blood neutrophil counts (5.3 vs 4.0 10(9)/L, P ≤ .001) and sputum eosinophilia (11.8% vs 0.8%, P ≤ .001). Multiple logistic regression analysis showed that increased blood neutrophil (odds ratio, 10.9; P = .002) and sputum eosinophil (odds ratio, 1.5; P = .005) counts were independently associated with severe adult-onset disease.
  
  
  CONCLUSIONS
  The majority of patients with severe adult-onset asthma are nonatopic and have persistent eosinophilic airway inflammation. This suggests that severe adult-onset asthma has a distinct underlying mechanism compared with milder disease.
authors.affiliation: Department of Respiratory Medicine, Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands. M.Amelink@amc.nl
authors.forename: Marijke
authors.initials: M
authors.lastname: Amelink
authors.forename: Jantina C
authors.initials: JC
authors.lastname: de Groot
authors.forename: Selma B
authors.initials: SB
authors.lastname: de Nijs
authors.forename: Rene
authors.initials: R
authors.lastname: Lutter
authors.forename: Aeilko H
authors.initials: AH
authors.lastname: Zwinderman
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Sterk
authors.forename: Anneke
authors.initials: A
authors.lastname: ten Brinke
authors.forename: Elisabeth H
authors.initials: EH
authors.lastname: Bel
mesh_terms: D000328:Adult; D017668:Age of Onset; D000368:Aged; D001249:Asthma / Q000150:complications* / Q000276:immunology / Q000503:physiopathology*; D004802:Eosinophilia / Q000209:etiology; D004804:Eosinophils / Q000737:chemistry / Q000473:pathology; D045853:Exhalation; D005260:Female; D006801:Humans; D007249:Inflammation / Q000150:complications / Q000473:pathology; D007958:Leukocyte Count; D008297:Male; D008875:Middle Aged; D009298:Nasal Polyps / Q000150:complications / Q000473:pathology; D009504:Neutrophils; D009569:Nitric Oxide / Q000378:metabolism; D009668:Nose Diseases / Q000150:complications / Q000473:pathology; D010641:Phenotype; D012720:Severity of Illness Index; D055815:Young Adult
chemical_list: D009569:Nitric Oxide
keywords: Asthma; BMI; Body mass index; Feno; Fraction of exhaled nitric oxide; OR; Odds ratio; adult onset; eosinophilia; sinus disease